为什么ColdFusion SESSION变量“未定义”之后被引用几行？ [英] Why is a ColdFusion SESSION variable "undefined" after being referenced a few lines before?

问题描述

在Windows2003 / IIS6上运行ColdFusion 8.01标准

Running ColdFusion 8.01 Standard on Windows2003/IIS6

Application.cfc：

Application.cfc:

<cfcomponent output="false">
    <cfscript>
        THIS.SessionManagement = "Yes";
        THIS.SessionTimeout = CreateTimeSpan(0, 3, 0, 0);
        THIS.ApplicationTimeout = CreateTimeSpan(0, 8, 0, 0);
    </cfscript>

    <cffunction name="onRequestStart" returnType="Boolean" output="false">
        <cfargument name="targetPage" type="string" required="true">

        <cfscript>
            if  (!StructKeyExists(SESSION, "User"))
                SESSION.User = CreateObject("component", "cfc.User");
        </cfscript>
    </cffunction>
</cfcomponent>

模板文件伪代码示例：

    LOCAL.qItems =
        CreateObject(
                "component",
                "cfc.Items"
                ).setUser(SESSION.User).getItems();

    for (i=1; i<=LOCAL.qItems.RECORDCOUNT; i++) {
        LOCAL.Item =
            CreateObject(
                "component",
                "cfc.Item"
                ).setUser(
                    SESSION.User
                    ).setId(LOCAL.qItems["Sku"][i]);
    }

SESSION.User已设置（如果尚未定义） <> c> c> c> onRequestStart（）。上面的代码运行在模板文件中。对 SESSION.User 的第二个引用已在元素USER在SESSION 中未定义时抛出异常。

SESSION.User is set (if not already defined) in onRequestStart() of Application.cfc. The above code runs in a template file. The second reference to SESSION.User has thrown an exception with the message Element USER is undefined in SESSION.

为什么SESSION.User在前几行定义（不抛出异常），然后在几行后（毫秒内）抛出这个异常？

Why would SESSION.User be defined (doesn't throw an exception) a few lines before, and then throw this exception a few lines later (within milliseconds)?

这可能在我的申请中每天在不同的模板中发生一次。

This happens maybe once a day in different templates throughout my application.

如何防止这种情况？ / p>

How can I prevent this?

推荐答案

这很可能是一个线程安全问题，在你的代码清除会话范围或分配NULL到 SESSION.User 。

It's most likely a thread safety issue with something else in your code clearing out session scope or assigning NULL to SESSION.User.

我建议，因为你似乎没有本地声明 i ，因此代码不是线程安全的，所以你可能在代码的其他地方有类似的错误。

I suggest that because you don't seem to have a local declaration for i in your loop, so that code is not thread safe - and so you may have similar errors elsewhere in your code.

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